Natural Resources Conservation Service Ecological site R029XY072NV VALLEY WASH Accessed: 09/23/2021 General information Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site. Figure 1. Mapped extent Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated. Associated sites R029XY017NV LOAMY 5-8 P.Z. R029XY020NV SILTY 5-8 P.Z. Similar sites R029XY041NV DRY WASH ERNAN5-ATCO codominant shrubs; less productive site R029XY009NV UPLAND WASH ARTR2 dominant shrub; higher elevations Table 1. Dominant plant species Tree Not specified Shrub (1) Atriplex canescens (2) Ambrosia eriocentra Herbaceous (1) Achnatherum hymenoides Physiographic features This site occurs in drainageways of inset fans and axial-stream terraces. Slopes range from 0 to 15 percent, but slope gradients of 2 to 8 percent are typical. Elevations are 4000 to about 5500 feet. Table 2. Representative physiographic features Landforms (1) Inset fan (2) Drainageway Elevation 4,000–5,500 ft Slope 0–15% Aspect Aspect is not a significant factor Climatic features The climate associated with this site is arid, characterized by cool, moist winters and hot, dry summers. Average annual precipitation is 5 to 8 inches. Mean annual air temperature is 49 to 60 degrees F. The average growing season is about 120 to 180 days. Table 3. Representative climatic features Frost-free period (average) 180 days Freeze-free period (average) 0 days Precipitation total (average) 8 in Influencing water features This site is frequently disturbed by intense, natural, flood flows. Soil features The soils associated with this site are deep alluvium from mixed sources. The soils are quite variable as they continue to be re-worked by water. These soils typically have high amounts of gravels and cobbles distributed throughout the soil profile as well as at the surface. The water intake rates are high, available water capacity is low, runoff is medium and soils are well drained. Ecological dynamics This site is frequently disturbed by intense, natural, flood flows. Hollyleaf bursage, burrobrush, and rabbitbrush are the dominant shrubs as the plant community begins to stabilize following major disturbance. Species likely to invade this site are annuals such as cheatgrass and mustards. Ratings of ecological condition and determinations of similarity index are not applicable to this site due to the inherent instability of the plant community. Fire Ecology: Fourwing saltbush is most common under regimes of infrequent fire and moderate browsing. Fire top-kills or kills fourwing saltbush, depending upon ecotype. Fourwing saltbush may sprout after top-kill. There is little mention of fire in relation to hollyleaf bursage in the literature. Downy rabbitbrush is usually top-killed by fire. It has high resin content, and both foliage and stems may be consumed, even with relatively high moisture content. Fuel distribution as well as overall fuel loading affects the potential survival of downy rabbitbrush. Downy rabbitbrush regenerates after fire by sprouting and by establishing from off-site seed. Nevada ephedra generally sprouts after fire damages aboveground vegetation. Underground regenerative structures commonly survive when aboveground vegetation is consumed by fire. However, severe fires may kill shallowly buried regenerative structures. Purple sage has a high tolerance to fire and will resprout following fire. Fire generally kills hollyleaf bursage. Indian ricegrass can be killed by fire, depending on severity and season of burn. Indian ricegrass reestablishes on burned sites through seed dispersed from adjacent unburned areas. State and transition model Figure 3. DRAFT STM Figure 4. DRAFT STM LEGEND State 1 Reference State Community 1.1 Reference Plant Community The reference plant community is dominated by fourwing saltbush and hollyleaf bursage. Potential vegetative composition is about 5% grasses, 15% annual and perennial forbs and 80% shrubs. Approximate ground cover (basal and crown) is less than 10 percent (~7%). Table 4. Annual production by plant type Low Representative Value High Plant Type (Lb/Acre) (Lb/Acre) (Lb/Acre) Shrub/Vine 160 400 560 Forb 30 75 105 Grass/Grasslike 10 25 35 Total 200 500 700 Additional community tables Table 5. Community 1.1 plant community composition Annual Production Foliar Cover Group Common Name Symbol Scientific Name (Lb/Acre) (%) Grass/Grasslike 1 Primary Perennial Grasses 10–50 Indian ricegrass ACHY Achnatherum hymenoides 3–15 – threeawn ARIST Aristida 3–15 – squirreltail ELEL5 Elymus elymoides 3–15 – needle and thread HECO26 Hesperostipa comata 3–15 – sand dropseed SPCR Sporobolus cryptandrus 3–15 – Forb 2 Perennial 12–75 Indian ricegrass ACHY Achnatherum hymenoides 3–15 – squirreltail ELEL5 Elymus elymoides 3–15 – needle and thread HECO26 Hesperostipa comata 3–15 – sand dropseed SPCR Sporobolus cryptandrus 3–15 – buckwheat ERIOG Eriogonum 3–15 – smoothstem MELA2 Mentzelia laevicaulis 3–15 – blazingstar beardtongue PENST Penstemon 3–15 – globemallow SPHAE Sphaeralcea 3–15 – 3 Annual 1–25 Shrub/Vine 4 Primary Shrubs 290–490 fourwing saltbush ATCA2 Atriplex canescens 150–200 – woolly fruit bur AMER Ambrosia eriocentra 100–150 – ragweed yellow rabbitbrush CHVIP4 Chrysothamnus viscidiflorus ssp. puberulus 25–75 – Nevada jointfir EPNE Ephedra nevadensis 10–40 – purple sage SADOI Salvia dorrii ssp. dorrii var. incana 5–25 – 5 Secondary Shrubs 25–75 yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 5–15 – brittlebush ENCEL Encelia 5–15 – rubber rabbitbrush ERNAN5 Ericameria nauseosa ssp. nauseosa var. 5–15 – nauseosa broom snakeweed GUSA2 Gutierrezia sarothrae 5–15 – burrobrush HYMEN3 Hymenoclea 5–15 – water jacket LYAN Lycium andersonii 5–15 – banana yucca YUBA Yucca baccata 5–15 – Animal community Livestock Interpretations: This site is suited to livestock grazing. Grazing management should be keyed to perennial grass production. Indian ricegrass has good forage value for domestic sheep, cattle and horses. It supplies a source of green feed before most other native grasses have produced much new growth. Fourwing saltbush is one of the most palatable shrubs in the West. Its protein, fat, and carbohydrate levels are comparable to alfalfa. It provides nutritious forage for all classes of livestock. Palatability is rated as good for domestic sheep and domestic goats; fair for cattle; fair to good for horses in winter, poor for horses in other seasons. Downy rabbitbrush is tolerant of grazing and may be rejuvenated by foliage removal. Downy rabbitbrush commonly increases on degraded rangelands as more palatable species are removed. Nevada ephedra is important winter range browse for domestic cattle, sheep and goats. Purple sage has low to medium platability for livestock. Stocking rates vary over time depending upon season of use, climate variations, site, and previous and current management goals. A safe starting stocking rate is an estimated stocking rate that is fine tuned by the client by adaptive management through the year and from year to year. Wildlife Interpretations: Fourwing saltbush provides valuable habitat and year-round browse for wildlife. Fourwing saltbush also provides browse and shelter for small mammals. Additionally, the browse provides a source of water for black-tailed jackrabbits in arid environments. Granivorous birds consume the fruits. Wild ungulates, rodent and lagomorphis readily consume all aboveground portions of the plant. Palatability is rated good for deer, elk, pronghorn and bighorn sheep. Downy rabbitbrush provides an important source of browse for wildlife, particularly in the late fall and early winter after more palatable species have been depleted. Wild ungulates show varying preference for Douglas’ rabbitbrush depending on season, locality, and subspecies. Mature or partially mature plants are generally preferred to green, immature ones. Downy rabbitbrush provides important cover for pronghorn fawns. In parts of the Great Basin, plants regrew rapidly after they were nearly completely consumed by spring-browsing black-tailed jackrabbits. Mule deer, bighorn sheep, and pronghorn browse Nevada ephedra, especially in spring and late summer when new growth is available. Purple sage has low to medium platability for wildlife. Indian ricegrass is an important forage for several wildlife species. Hydrological functions Runoff is medium. Recreational uses Aesthetic value is derived from the diverse floral and faunal composition and the colorful flowering of wild flowers and shrubs during the spring and early summer. This site offers rewarding opportunities to photographers and for nature study. This site is used for camping and hiking and has potential for upland and big game hunting. Other products Fourwing saltbush is traditionally important to Native Americans. They ground the seeds for flour. The leaves, placed on coals, impart a salty flavor to corn and other roasted food. Top-growth produces a yellow dye. Young leaves and shoots were used to dye wool and other materials. The roots and flowers were ground to soothe insect bites. Downy rabbitbrush can be a source of rubber and possibly valuable resins. Native Americans used Nevada ephedra